BG 17.26

17.26 सद्भावे in the sense of reality? साधुभावे in the sense of goodness? च and? सत् Sat? इति thus? एतत् this? प्रयुज्यते is used? प्रशस्ते auspicious? कर्मणि (in the sense of) an act? तथा so also? सत् Sat? शब्दः word? पार्थ O Partha? युज्यते is used.Commentary Satbhava That which is unchanging amidst the changing? that which is permanent amidst the impermanent? that which exists in the past? present and future is Sat the reality behind the everchanging names and forms is Sat the substratum in which the everchanging forms inhere is Sat. Meritorious action is Sat.Sadhubhava An attribute of harmony with nature? so that the worlds cycle moves smoothly.The word Sat is powerful enough to make a defective action perfect and complete. When a good action is likely to be rendered Asat or bad owing to a single defect? the use of the word Sat makes it free from defects and brings it to a successful termination. The word Sat removes the evil ality of the action as it has the power of purifying and rendering the act perfect.Sat is Existence Absolute. Sat is Para Brahman. Sat is the inexpressible symbol of that mysterious indescribable? illimitable? indivisible? selfluminous? immortal Brahman.The word Sat is used when you wish to express the reality of an object which is unreal or which is relatively real? as for instance? the birth of a son who is unreal or relatively real in telling that a man is one of good conduct when his conduct is not good or is only relatively good? and in expressing that an act is auspicious? when it is not auspicious or only relatively auspicious.Brahman alone is real. It alone really exists. But we say when a son is born to Mr. Govindan that Mr. Govindans son has come into existence. From the viewpoint of Brahman or Existence Absolute? Mr. Govindans son never exists.The word Sat which is only applied to Brahman is used also for Mr. Govindans son who is unreal or relatively real. Brahman alone is absolutely good and absolutely auspicious. But the,word Sat that can properly be applied to Brahman alone is applied to an act which is not auspicious or which is only relatively auspicious. The use of Sat renders the imperfectly performed actions perfect.

— vedicscriptures · exposition · source ↗

The words praśaste karmaṇi, or “prescribed duties,” indicate that there are many activities prescribed in the Vedic literature which are purificatory processes, beginning from the time of conception up to the end of one’s life. Such purificatory processes are adopted for the ultimate liberation of the living entity. In all such activities it is recommended that one vibrate oṁ tat sat. The words sad-bhāve and sādhu-bhāve indicate the transcendental situation. Acting in Kṛṣṇa consciousness is called sattva, and one who is fully conscious of the activities of Kṛṣṇa consciousness is called a sādhu. In the Śrīmad-Bhāgavatam (3.25.25) it is said that the transcendental subject matter becomes clear in the association of the devotees. The words used are satāṁ prasaṅgāt. Without good association, one cannot achieve transcendental knowledge. When initiating a person or offering the sacred thread, one vibrates the words oṁ tat sat. Similarly, in all kinds of performance of yajña the object is the Supreme, oṁ tat sat. The word tad-arthīyam further means offering service to anything which represents the Supreme, including such service as cooking and helping in the Lord’s temple, or any other kind of work for broadcasting the glories of the Lord. These supreme words oṁ tat sat are thus used in many ways to perfect all activities and make everything complete.

— vedicscriptures · exposition · source ↗